Pararobertsite Mineral Data
General Pararobertsite Information
Chemical Formula:
Ca2Mn+++3(PO4)3O2•3(H2O)
Composition:
Molecular Weight = 615.93 gm
Calcium 13.01 % Ca 18.21 % CaO
Manganese 26.76 % Mn 38.45 % Mn2 O3
Phosphorus 15.09 % P 34.57 % P2 O5
Hydrogen 0.98 % H 8.77 % H2 O
Oxygen 44.16 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Ca2 Mn3+ 3 (PO4 )3 O2 •3(H2 O)
Environment:
Rare secondary mineral in a complex zoned granite pegmatite.
IMA Status:
Approved IMA 1989
Locality:
Tip Top mine, 8.5 km southwest of Custer, Custer Co., South Dakota, USA. Link to MinDat.org Location Data.
Name Origin:
From the Greek para, for near, and its relation to robertsite.
Name Pronunciation:
Pararobertsite + Pronunciation
Synonym:
ICSD 89712
PDF 45-1440
Pararobertsite Image
Images:
Pararobertsite
Comments: SEM image of a group of pararobertsite crystals illustraing the typical habit. (CanMin, v27:451).
Location: Tip Top pegmatite, Custer County, South Dakota, USA.
Scale: Scale Bar 100 µm.
© Canadian Mineralogist
Pararobertsite Crystallography
Axial Ratios:
a:b:c =0.6656:1:0.8362
Cell Dimensions:
a = 8.825, b = 13.258, c = 11.087, Z = 4; beta = 101.19° V = 1,272.54 Den(Calc)= 3.21
Crystal System:
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 21 /c
X Ray Diffraction:
By Intensity(I/Io ): 8.69(1), 2.884(0.6), 5.66(0.6),
Physical Properties of Pararobertsite
Cleavage:
{100} Perfect
Color:
Bronze, Yellow, Dark red.
Density:
3.22
Diaphaneity:
Transparent
Hardness:
2 - Gypsum
Luster:
Vitreous (Glassy)
Streak:
brown red
Optical Properties of Pararobertsite
Gladstone-Dale:
CI meas = -0.018 (Superior) - where the CI = (1-KPDmeas /KC ) CI calc = -0.021 (Excellent) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2523,KPDmeas = 0.2516,KC = 0.2471 Ncalc = 1.79 - 1.8
Optical Data:
Biaxial (-), a=1.79, b=1.81, g=1.83, bire=0.0400, 2V(Calc)=88, 2V(Meas)=84.
Calculated Properties of Pararobertsite
Electron Density:
Bulk Density (Electron Density)=3.16 gm/cc note: Specific Gravity of Pararobertsite =3.22 gm/cc.
Fermion Index:
Fermion Index = 0.0003891242 Boson Index = 0.9996108758
Photoelectric:
PEPararobertsite = 9.13 barns/electronU=PEPararobertsite x r Electron Density= 28.83 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Pararobertsite is Not Radioactive
Pararobertsite Classification
Dana Class:
42.08.05.02 (42) Hydrated Phosphates, etc., Containing Hydroxyl or Halogen
(42.08) where (AB)7 (XO4)4 Zq � x(H2O)
(42.08.05) Kolfanite Group
42.08.05.01 Kolfanite Ca2Fe3O2(AsO4)3•2(H2O) A2/a 2/m
42.08.05.02 Pararobertsite Ca2Mn3(PO4)3O2•3(H2O) P 21 /c 2/m
42.08.05.03 Sailaufite ! Ca2Mn3O2(AsO4)2(CO3)•3(H2O) Cm m
Strunz Class:
08.DH.30 08 - PHOSPHATES, ARSENATES, VANADATES
08.D - Phosphates, etc
08.DH -With large and medium-sized cations, (OH, etc.):RO4 < 1:1
08.DH.30 Arseniosiderite Ca2Fe3(AsO4)3O2•3(H2O) A2/a 2/m
08.DH.30 Pararobertsite Ca2Mn3(PO4)3O2•3(H2O) P 21 /c 2/m
08.DH.30 Kolfanite Ca2Fe3O2(AsO4)3•2(H2O) A2/a 2/m
08.DH.30 Lunokite (Mn,Ca)(Mg,Fe,Mn)Al(PO4)2(OH)•4(H2O) P bca 2/m 2/m 2/m
08.DH.30 Robertsite Ca6Mn9(PO4)9O6(H2O)6•3(H2O) A2/a 2/m
08.DH.30 Mitridatite Ca2Fe3(PO4)3O2•3(H2O) A2/a 2/m
08.DH.30 Sailaufite ! Ca2Mn3O2(AsO4)2(CO3)•3(H2O) Cm m
Other Pararobertsite Information
References:
NAME( AntBidBlaNic4) PHYS. PROP.(Am.Min.,Vol.75,p1211,1990) OPTIC PROP.(Am.Min.,Vol.75,p1211,1990)
See Also:
Links to other databases for Pararobertsite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - MinDAT
10 - Mineralienatlas (Deutsch)
11 - Online Mineral Museum
12 - QUT Mineral Atlas
13 - Ruff.Info
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Pararobertsite
Ca2Mn+++3(PO4)3O2•3(H2O)
Dana No: 42.08.05.02 Strunz No: 08.DH.30
Locality:
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